This document discusses various processes involved in water treatment, including sedimentation, coagulation, filtration, disinfection, and water softening. It also covers types of sedimentation and filtration tanks, factors affecting sedimentation, coagulation chemicals and feeders, and chlorination. Distribution systems are also summarized, including types of supply systems, layouts, and functions of service reservoirs. Key factors in reservoir sizing such as storage capacities are also outlined.

1. UNIT-II

2. CHAPTER 2.1
TREATMENT OF WATER

3. SEDIMENTATION
• It is the process of causing heavier solid
particles in suspension both organic and
inorganic, to settle by retaining water in a
basin

4. Sedimentation

5. THEORY OF SEDIMENTATION
• The particles heavier than water tends to
settle down due to force of gravity.
• Impurities in water are held in suspension
due to the turbulence of the moving water.
• When the velocity of flow is reduced, the
suspended particles tend to settle down at the
bottom of the tank.
• This phenomenan is known as hydraulic
subsidence.

6. FACTORS AFFECTING SEDIMENTATION
• Size, shape and weight of the particle
• Viscosity and temperature of water
• Surface overflow
• Surface area
• Velocity of flow
• Inlet and outlet arrangements
• Detention period

7. • Effective depth of settling tank
• Concentration of suspended matter
• Wind blow on the surface area of the basin
• Biological, electrical and other forces

8. TYPES OD SEDIMENTAION
• PLAIN SEDIMENTATION
• SEDIMENTATION WITH COAGULATION

9. PLAIN SEDIMENTATION
• The raw water is retained for sometime in a
basin for the suspended particles to settle
down by the action of gravity.

10. SEDIMENTATION WITH COAGULATION
• In this some chemical compounds called
coagulants are added to water to assist
sedimentation.

11. Coagulation

12. Classification of sedimentation tank
• Nature of working
 Fill and draw type
 Continuous flow type
• Direction of flow
 Horizontal flow basin
 Vertical or upward flow basin
 Radial flow basin
 Spiral or circumferential flow basin

13. • Shape
 Rectangular(horizontal flow) tanks.
 Circular (vertical, radial, circumferential flow)
tanks.
 Hopper bottom (radial flow) tanks.

14. FILL AND DRAW TYPE
• The raw water is allowed to rest on the basin
for sometime.
• During that time the suspended particles
settle down at the bottom.
• The clear water is drawn off and the deposits
are cleaned.
• Then the basins is refilled and the action
continues.

16. CONTINUOUS FLOW TYPE
• The raw water is allowed to flow through the
tank continuously with a small uniform
velocity.
• Within the detention time the suspended
particles settle down at the bottom before
they reach the exit.
• The inlets and outlets are so designed that
they cause least disturbance to the flowing
water in the tank.

18. HORIZONTAL FLOW BASIN
• It is a rectangular plan having length is twice
or thrice the breadth.
• The floor is given a slope to facilitate sludge
removal.

19. VERTICAL OR UPWARD FLOW BASIN
• It is deep and circular or rectangular with
hopper bottom.
• The raw water enters the basin vertically from
bottom through the centrally located vertical
inlet pipe.
• The suspending particle settle down at the
hopper bottom and is collected through the
sludge pipe.

21. RADIAL FLOW BASIN

22. • The water enters through the central inlet
pipe.
• The inlet pipe is enclosed with the deflector
box which deflects the flow downwards.
• Then the flow goes out radially towards the
circumference of the tank.
• During the radial flow all the settleable
particles settle down.

23. SPIRAL OR CIRCUMFERENCE FLOW
BASIN

24. • The water enters the tank through two or
three vertical slits of the inlet channel.
• A rotating arm is provided in the tank.
• It makes all the water in the tank to move
circumferentially.
• As the flow is very slow all the settleable
particles settle at the bottom of the tank.
• Clear water is drawn through weir type outlet.

25. DEFINITION IN COAGULATION OF
WATER
• The process of addition and mixing of
coagulants is coagulation.
• The process of addition of coagulants in
correct amount is called dosing.
• The process of floc formation is termed as
flocculation.
• The coagulation is adopted when the turbidity
of raw water exceeds 30 to 50 ppm.

26. Objectives of coagulants
• To unite several fine colloidal particles
together.
• To react with impurities in water and make
them to settle.
• To prepare raw water fit for filtration.
• To expedite quick sedimentation.
• To remove certain extent turbidity, organic
and inorganic matter.

27. COMMON COAGULANTS
• Sodium aluminate
• Ferric chloride
• Ferric sulphates
• Betonite clay
• Fuller’s earth
• Magnesium carbonate
• Polyelectolytes

28. COAGULANT FEEDERS
• The coagulants may be fed in powder form
(dry feeding) or in solution form (wet feeding)
Dry feeders
Wet feeders

29. DRY FEEDERS

30. WET FEEDERS

31. COAGULANT MIXERS
• The success of floc formation mainly depends
upon the through mixing of coagulant with raw
water
• The violent mixing is carried out by the following
devices
Centrifugal pump
Compressed air
Mixing channel
Mixing basin

32. Mixing basins with baffle walls
• Horizontal or round the end type
• Vertical or over and under the baffle type

34. Mixing basins with mechanical devices
• Flash mixers
• Flocculators

36. DOSAGE OF COAGULANTS
• Kind of coagulants
• Amount of coagulants
• Time of mixing
• Violence of agitation
• Time of settlement
• Amount and character of colour
• Turbidity of water
• Ph of water
• Temperature of water

37. FILTRATION
• Filtration is the process of passing the water
through filter beds.
• Filtration is the most important stage in the
purification of water.
• Filtration removes colour, odour, turbidity and
pathogenetic bacteria from water
• It also changes the chemical characteristics of
water.

38. THEORY OF FILTRATION
Mechanical straining
Sedimentation and absorption
Biological metabolism of bacterial action
Electrolytic changes

40. FILTER SAND
• Sand having effective size of 0.25 to 0.35 mm
are used for slow sand filters
• Sand having effective size of 0.35 to 0.60 mm
are used for rapid sand filters
• For slow sand filters the depth of sand bed is
0.60 to 1m.
• For slow sand filters the depth of sand bed is
0.60 to 0.9m.

41. TYPES OF FILTERS
• Slow sand filters
• Rapid sand filters
• Pressure filters

46. DISINFECTION OF WATER
• Disinfection of water is the process of removal
of pathogenic bacteria from water by
chemicals.
• The chemicals used for killing disease
producing bacteria is known as disinfectants.
• Sterilisation is the process of killing all bacteria
by boiling.

47. METHODS OF DISINFECTION
• Boiling
• Excess lime treatment
• Iodine and bromine treatment
• Ozone treatment
• Potassium permanganate treatment
• Silver treatment
• Ultra violet ray treatment

48. CHLORINATION
• Chlorination is the treatment of water with
chlorine for disinfection of water.
• Chlorination not only disinfectants, but also
removes colour, odour, unpleasant taste and
prevent the growth of weeds in water.

49. FORMS OF CHLORINATION
• As bleaching powder
• As chloromines
• As chlorine-di-oxide
• As free chlorine gas
• As liquid chlorine

50. • Dosage of chlorine
• Residual chlorine
• Contact period

51. WATER SOFTENING
• Water softening is the process of reduction of
hardness of water
Purpose of water softening
To reduce soap consumption
To reduce corrosion
To improve the taste of food
To reduce scaling in boilers

52. HARDNESS OF WATER
• It is caused by the presence of certain salts of
calcium and magnesium dissolved in water.
• It s the characteristic which prevents the
lathering of soap.
• TYPES OF HARDNESS
Temporary hardness
Permanent hardness

53. REMOVAL OF HARDNESS
• Removal of temporary hardness
• Removal of permanent hardness
Lime – soda process
Zeolite process
Demineralisation

54. MISCELLANEOUS METHODS FOR
TREATMENT
• Removal of colour, odour, taste
Aeration
Activated carbon treatment
Copper sulphate treatment
Oxidation of organic matter
• Removal of iron and manganese
• Fluoridation and defluoridation

55. REVERSE OSMOSIS PROCESS

56. CHAPTER 2.2
DISTRIBUTION SYSTEM

57. GENERAL REQUIREMENTS
• It should be capable of supplying water in
adequate quantities.
• It should meet the demand of water supply for
fire fighting purposes.
• It should be economical in its design, layout and
construction.
• It should be easy and simple to operate and
repair.
• It should be safe against any future pollution of
water

58. • It should be water tight.
• It should be safe as not to cause the failure of
the pipe line.
• It should provide free circulation of water.
• The sanitation of the water distribution area
should be good so that the possibilities of
pollution are remote during repairs or
replacement of pipes.

59. DIFFERENT SYSTEMS OF SUPPLYING
WATER
Systems of conveyance and distribution
Systems of water supply
Systems of distribution layout

60. SYSTEMS OF CONVEYANCE AND
DISTRIBUTION
• Gravity system
• Pumping system
• Combined pumping and gravity system

61. SYSTEM OF WATER SUPPLY
• Continuous system
• Intermittent system.

62. SYSTEM OF DISTRIBUTION LAYOUT
• Dead end or tree system
• Grid iron system
• Circular or ring system
• Radial system

63. SERVICE RESERVOIRS
• Service reservoir are also known as
distribution reservoir.
• They are the tanks constructed to store
treated water which may be used when
required.

64. FUNCTIONS OF SERVICE RESERVOIR
• To store water for emergencies like breakdown
of pumps, fires, power supply failures etc…
• To facilitate constant rate of pumping and thus
reduce pumping hours.
• Under gravity system of supply, to minimise
the diameter of mains.
• To make the design and construction of
treatment units and distribution system
economical.

65. TYPES OF SERVICE RESERVOIR
• SURFACE RESERVOIR
• ELEVATED RESERVOIR

66. CAPACITY OF SERVICE RESERVOIR
Balancing storage
Breakdown storage
Fire storage

67. FACTORS AFFECTING CAPACITY OF
RESERVOIRS
• The variation between maximum and
minimum demands.
• The reserve required for emergencies like fire
or breakdown of pumps.
• The standby pumping capacity.
• Interconnections in the distribution mains.